Optical multi-dimensional coherent spectroscopy (MDCS) is an extremely powerful technique developed over the last two decades for studying structure and ultrafast dynamics. Specifically, MDCS is a non-linear optical technique based on concepts originating in nuclear magnetic resonance (NMR) spectroscopy that enabled the determination of molecular structure. Its empowering features include the capacities to decouple homogeneous and inhomogeneous linewidths, to identify couplings between the excited states, and to track the energy redistribution (in real time) in complex systems. MDCS uses a sequence of (typically three) laser pulses to excite the sample. A multi-dimensional spectrum is then generated by calculating Fourier transforms of the signal with respect to the time delays between pulses and the time period during which the signal is emitted. However, current MDCS implementations have long acquisition times (when implemented with mechanical delay stages) and/or limited spectral resolution (e.g., >10 GHz, limited by spectrometer resolution or the achievable time delays). These attributes limit their applications for studying atomic systems and performing molecular fingerprint ro-vibrational spectroscopy. In addition, MDCS has not been used beyond research laboratories because of the bulky arrangements and complex phase cycling schemes necessary to suppress background linear signals.
This disclosure proposes to overcome these weaknesses of MDCS by leveraging the technique of dual comb spectroscopy (DCS), which has emerged as a revolutionary optical method that enables the rapid acquisition of high resolution, broad absorption spectra.
This section provides background information related to the present disclosure which is not necessarily prior art.